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SECURITIES AND EXCHANGE COMMISSION (Release No. 34-64228; File No. SR-CHX-2011-06) April 7, 2011 Self-Regulatory Organizations; Chicago Stock Exchange, Inc.; Notice of Filing and Immediate Effectiveness of Proposed Rule Change to Extend the Pilot Program Relating to Clearly Erroneous Transactions Pursuant to Section 19(b)(1) of the Securities Exchange Act of 1934 (“Act”) 1, and Rule 19b-4 2 thereunder, notice is hereby given that on April 5, 2010, the Chicago Stock Exchange, Inc. (“CHX” or the “Exchange”) filed with the Securities and Exchange Commission (“Commission”) the proposed rule change as described in Items I and II below, which Items have been prepared by the CHX. CHX has filed this proposal pursuant to Exchange Act Rule 19b4(f)(6) 3 which is effective upon filing with the Commission. I. Self-Regulatory Organization’s Statement of the Terms of Substance of the Proposed Rule Change CHX proposes to amend its rules to extend the pilot program relating to clearly erroneous transactions. The text of this proposed rule change is available on the Exchange’s Web site at (www.chx.com) and in the Commission’s Public Reference Room. II. Self-Regulatory Organization’s Statement of the Purpose of, and Statutory Basis for, the Proposed Rule Change In its filing with the Commission, the CHX included statements concerning the purpose of and basis for the proposed rule changes and discussed any comments it received regarding the proposal. The text of these statements may be examined at the places specified in Item IV below. The CHX has prepared summaries, set forth in sections A, B and C below, of the most